…you purchase a book you’ve already read?
I bought Singularity Sky by Charles Stross with Christmas gift-card money. I brought it home and set it aside for when I was done with the other books I was reading. A few nights ago, I picked it up, started reading, and immediately said (out loud), “awww crap.”
Oops. I guess I should read the first page of every book I buy from now on.